President Trump has decided to pull the U.S. out of the Paris Agreement. Here's what you need to know. (Daron Taylor/The Washington Post)

President Trump's decision to leave the Paris climate-change deal has all the hallmarks of a base-pleasing move — and none of the signs of a decision that will have any major political consequences for him.

According to polls, most Americans disagree with what he just decided. Even Republicans are split about whether they wanted him to stay or leave the Paris deal.

In fact, to pull one more number from that January Washington Post-ABC News poll, only 23 percent of Republicans strongly support Trump leaving the world's premier international climate deal.

And a 2015 Gallup poll found that only the most conservative Republicans think climate change won't affect them in their lifetime.

In other words: The people applauding Trump's decision to leave Paris are Trump's hardcore base. Which means Trump just made a decision that wins over exactly no one who wasn't already his supporter.

Take Carmel, Ind., a suburb of Indianapolis about 100,000 people strong. The six-term GOP mayor, Jim Brainard, figures his town is about 70 to 85 percent Republican. But Trump won the city with only 56 percent of the vote, he said.

“I don't understand what he's politically doing,” said Brainard, an advocate of the need to address climate change. “There are probably a lot of moderate Republicans around the country that very reluctantly voted for him and will probably not vote for him again, given a different alternative. It would seem prudent to me to try to expand his base.”

Okay, let's flip that logic around. If Trump just made a politically unpopular decision, it would seem like an easy thing for Democrats to capitalize on, right?

Right?

Not when you consider this: Environmentalists have been trying in vain for years to turn this into a winning issue. But the people who don't like climate-change regulations have been much more successful resonating with voters than the environmentalists, analysts say.

Part of the reason is that the environmentalists have a more difficult story to sell, said Seth Jaffe, a longtime environmental lawyer based in Boston. “When you ascribe Hurricane Sandy specifically to climate change, that's a hard one to be definitive about,” he said. “And you need to be definitive, because those are the things that move people.”

Meanwhile, Trump — ever the master marketer — can say this: “The Paris climate accord is simply the latest example of Washington entering into an agreement that disadvantages the U.S.”

It's short. It's on message with his economic populism. It doesn't require anyone to envision how a few inches of ocean rising in the Arctic might affect their skiing plans.

And that might help explain why, when Gallup pollsters called Americans in May and asked them to name the most important problem facing the country today, just 2 percent said the environment and/or pollution. (The top vote-getter in this open-ended question: dissatisfaction with the government, at 18 percent).

Of course, Trump's decision to leave the Paris accord isn't risk-free, politically speaking. He is gambling with the one thing politicians can't predict or measure — the weather.

“We know from disaster studies that people look at one particular event and it raises their consciousness, at least for a little while,” said Laura Hatcher, a political and climate scientist at Southeast Missouri State University.

Early indications are that Democrats, seeking to unseat Republicans in the 2018 midterm elections, will try to frame Trump's decision to leave Paris as an economic cost for voters, in line with how Republicans' health-care bill could raise premiums for some.

“On climate change Trump is exacerbating a national security emergency while threatening the Made-in-America exports that grow our economy,” Jessica Mackler, president of the Democratic super PAC American Bridge, in a statement to The Fix.

Combine this high-profile (if mostly symbolic) decision to leave the Paris agreement with a devastating flood or hurricane that captures the nation's attention right before the 2018 elections, with successful Democratic messaging, and Trump could be setting himself up for a situation he can't back out of.

“All he needs is one negative climate event close to the midterm election,” Hatcher said, “and he will have cost himself politically.”

Except that scenario — the one where leaving his Paris withdrawal decision costs Trump politically — carries with it a lot of ifs.

From Trump's perspective, the immediate benefits to leave the Paris agreement are much more clear: It doesn't win him any new friends, but it does shore up the friends he's got.